Menu

6. Spine MCQs

Practice Set 108 of 379

This practice set contains high-yield board review questions covering key concepts in 6. Spine. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 2141

Topic: 6. Spine

Figures 21a and 21b show the radiographs of a 22-year-old man who was shot through the abdomen the previous evening. An exploratory laparotomy performed at the time of admission revealed a colon injury. Current examination reveals no neurologic deficits. Management for the spinal injury should include

. oral antibiotics for staphylococcus for 48 hours.
. oral broad-spectrum antibiotics for 7 days.
. IV antibiotics for staphylococcus for 48 hours.
. IV broad-spectrum antibiotics for 48 hours.
. IV broad-spectrum antibiotics for 7 days.

Correct Answer & Explanation

. IV broad-spectrum antibiotics for 7 days.

Explanation

DISCUSSION: IV broad-spectrum antibiotics should be administered for 7 days.  This regimen, when compared to fragment removal or other antibiotic regimens, has been shown to reduce the incidence of spinal infections and reduce the need for metallic fragment removal with perforation of a viscus.REFERENCES: Roffi RP, Waters RL, Adkins RH: Gunshot wounds to the spine associated with a perforated viscus.  Spine 1989;14:808-811.Velmahoos GC, Demetriades D: Gunshot wounds of the spine: Should retained bullets be removed to prevent infection?  Ann R Coll Surg Engl 1976;94:85-87.

Question 2142

Topic: 6. Spine

Figures 21a and 21b show the radiographs of a 12-year-old patient with an L4-level myelomeningocele who has scoliosis that has been slowly progressing for the past several years. There has been no loss of motor function. An MRI scan shows no syringomyelia or increased hydrocephalus. Management should consist of

. follow-up with repeat radiographs in 6 months.
. brace treatment.
. posterior spinal fusion with instrumentation.
. anterior and posterior spinal fusion with instrumentation.
. anterior spinal fusion with instrumentation.

Correct Answer & Explanation

. anterior and posterior spinal fusion with instrumentation.

Explanation

DISCUSSION: Scoliosis is a common occurrence in children with myelomeningocele, with the incidence increasing as the neurologic level moves cephalad.  The rate of pseudarthrosis for isolated anterior or posterior fusions has been reported as high as 75%.  The combination of anterior and posterior fusions with some type of instrumentation has been shown to decrease the rate of pseudarthrosis to 20%.  Brace treatment in smaller curves can be used as a temporizing measure to delay surgery, but as with idiopathic scoliosis, the brace is ineffective for larger curves.  Observation is not indicated with a curve of this magnitude.REFERENCES: Ward WT, Wenger DR, Roach JW: Surgical correction of myelomeningocele scoliosis: A critical appraisal of various spinal instrumentation systems.  J Pediatr Orthop 1989;9:262-268.Muller EB, Nordwall A: Brace treatment of scoliosis in children with myelomeningocele.  Spine 1994;19:151-155.

Question 2143

Topic: 6. Spine

A 36-year-old man has a 2-day history of acute lower back pain with severe radicular symptoms in the left lower extremity. The patient has a positive straight leg test at 40 degrees on the left side and mild decreased sensation on the dorsum of the left foot. What is the most appropriate management at this time? Review Topic

. Urgent admission to the hospital for surgical intervention
. Immediate MRI of the lumbar spine as an outpatient
. Anti-inflammatory medications and activity modification
. Caudal epidural steroid injection
. Electromyography

Correct Answer & Explanation

. Anti-inflammatory medications and activity modification

Explanation

In the absence of any severe progressive neurologic deficits or other red flags, the most appropriate management for an acute lumbar disk herniation is nonsurgical care. Conservative treatments such as limited bed rest, anti-inflammatory medications, and judicious use of pain medications are appropriate in this clinical situation. Up to 90% of patients will experience a resolution of symptoms without the need for surgical intervention within a 3-month window. In the acute setting, with no neurologic deficits, immediate MRI of the lumbar spine is neither beneficial nor warranted. Likewise, without signs of an acute deficit, emergent surgical intervention and caudal epidural steroid injections are not needed.

Question 2144

Topic: 6. Spine

A 42-year-old man with a history of renal cell carcinoma has progressive weakness in the lower extremities for the past 3 weeks. The patient desires intervention. A sagittal T 2 -weighted MRI scan is shown in Figure 9a, and a sagittal contrast enhanced T 1 -weighted MRI scan is shown in Figure 9b. He currently ambulates minimal distances with a walker. His life expectancy is 8 months. Treatment of the spine lesion should consist of

. radiation therapy.
. posterior laminectomy.
. anterior corpectomy and reconstruction.
. posterior laminectomy and fusion.
. kyphoplasty.

Correct Answer & Explanation

. anterior corpectomy and reconstruction.

Explanation

DISCUSSION: The MRI scans show a metastatic lesion in two contiguous vertebral bodies in the lower thoracic spine.  Posterior laminectomy is not indicated because this does not adequately decompress the neural elements and will lead to progressive kyphosis.  A posterior fusion may prevent progressive kyphosis but will not decompress the spinal cord.  Renal cell carcinoma is not radiosensitive; therefore, radiation therapy would not be helpful in relieving neurologic compression.  The lesion should be treated by an anterior corpectomy and reconstruction.  This will allow for complete decompression as well as reconstruction of the anterior column.  Kyphoplasty is not indicated in a lesion with disruption of the posterior cortex and neurologic impairment.REFERENCES: Spivak JM, Connolly PJ (eds): Orthopaedic Knowledge Update: Spine 3.  Rosemont, IL, American Academy of Orthopaedic Surgeons, 2006, pp 351-366.White AP, Kwon BK, Lindskog DM, et al: Metastatic disease of the spine.  J Am Acad Orthop Surg 2006;14:587-598.

Question 2145

Topic: 6. Spine

Figures 81a through 81c show the MRI scans of a 53-year-old man who has experienced a long history of progressively worsening right-sided back pain with radiation to the buttocks and right lower extremity. Examination reveals weakness and hyperreflexia in the right lower extremity. He reports intermittent episodes of urinary incontinence. What is the most appropriate surgical approach? Review Topic

. Costotransversectomy
. Laminectomy
. Transpedicular
. Lateral extracavitary
. Transthoracic

Correct Answer & Explanation

. Transpedicular

Explanation

The presence of stenosis in the thoracic region with its related clinical manifestations has only recently been appreciated. The pathogenesis of thoracic stenosis is similar to that found in the cervical or lumbar spine. Two distinct clinical syndromes of thoracic stenosis have been identified, the most common being associated with degenerative changes of the spine. Clinical manifestations include development of unilateral or bilateral symptoms of pseudoclaudication. Focal radicular pain or paresthesias may also be present. The neurologic examination initially may be normal, but as the degree of neural compression progresses, posterior column dysfunction and long tract signs appear. If allowed to progress untreated, the patient may develop significant difficulty with gait and bowel/bladder function. Thoracic spinal cord stenosis secondary to congenital narrowing of the spinal canal is associated with a more abrupt onset of symptoms. The typical clinical manifestations of myelopathy may commence following minor or moderate trauma. Radicular symptoms are rare in congenital thoracic stenosis. One indication for thoracic laminectomy is a patient in whom imaging has demonstrated evidence of spinal canal stenosis secondary to hypertrophy of the posterior elements. A laminectomy should not be the primary approach when stenosis results from a significant ventral epidural osteophyte or herniated disk; these lesions are more effectively and safely managed by a posterolateral (transpedicular, transfacetal, or costotransversectomy) or an anterior approach.

Question 2146

Topic: 6. Spine

A skeletally mature 15-year-old girl who was thrown from the car in a rollover accident sustained the injuries shown in Figures 23a through 23d. Examination reveals no neurologic deficit, but the patient has moderate posterior spinal tenderness at the level of the injury. What is the most appropriate treatment?

. Chairback brace
. Thoracolumbosacral orthosis (TLSO) molded in extension
. Posterior stabilization of the fracture with segmental fixation and iliac crest bone grafting
. Anterior corpectomy, strut grafting, and plating
. Combined anterior corpectomy, structural grafting and plating, and posterior stabilization and fusion

Correct Answer & Explanation

. Chairback brace

Explanation

DISCUSSION: The majority of patients with thoracolumbar burst fractures without neurologic deficit can be effectively treated with a TLSO or a hyperextension body cast.  Indications for surgery are neurologic deficit and/or significant deformity (greater than 50% loss of anterior vertebral body height or marked kyphosis).REFERENCES: Garfin SR, Vaccaro AR (eds): Orthopaedic Knowledge Update: Spine.  Rosemont, IL, American Academy of Orthopaedic Surgeons, 1997, pp 197-217.Chow GH, Nelson BJ, Gebhard JS, Brugman JL, Brown CW, Donaldson DH: Functional outcome of thoracolumbar burst fractures managed with hyperextension casting or bracing and early mobilization.  Spine 1996;21:2170-2175.

Question 2147

Topic: 6. Spine

In patients without spondylolisthesis or scoliosis undergoing laminectomy for lumbar spinal stenosis, spinal fusion is generally recommended if Review Topic

. a dural tear is repaired.
. more than one level requires decompression.
. less than one half of each facet is removed bilaterally.
. the pars interarticularis is fractured.
. the patient is a smoker.

Correct Answer & Explanation

. a dural tear is repaired.

Explanation

With the notable exception of fusion for degenerative spondylolisthesis and scoliosis, there is a paucity of evidence on the indications for spinal fusion in patients undergoing laminectomy for spinal stenosis. However, it is generally recommended that if the spine is destabilized (for example by removal of one complete facet joint or by an iatrogenic pars fracture), spinal fusion should be considered. Although fusion can be considered for a very long laminectomy, a two-level laminectomy does not represent, by itself, a clear indication for the addition of a spinal fusion. The repair of a dural tear and the use of nicotine by the patient play no role in the determination of whether or not to add fusion to a laminectomy procedure.

Question 2148

Topic: 6. Spine

A 67-year-old retired steelworker was involved in a motor vehicle accident and sustained a midcervical spinal cord injury. Radiographs and MRI scans reveal severe cervical stenosis and spondylosis without fractures or dislocations. Neurologic examination reveals an ASIA C spinal cord impairment with greater motor involvement of the upper extremities than the lower extremities. What is the probability that the patient eventually will become ambulatory?

. 2% to 5%
. 15% to 20%
. 35% to 45%
. 60% to 70%
. Greater than 90%

Correct Answer & Explanation

. 35% to 45%

Explanation

DISCUSSION: The patient sustained an incomplete spinal cord injury known as central cord syndrome.  Central cord syndrome characteristically has disproportionate involvement of the upper extremities with the lower extremities being relatively spared.  It is most commonly seen after cervical injuries in elderly patients with spondylosis and spinal stenosis, often without fracture.  Penrod and associates noted that 23 of 59 patients with central cord syndrome(ASIA C and D) ultimately walked.  The poorest prognosis, however, was in ASIA C patients older than age 50, in which only 40% walked.REFERENCES: Penrod LE, Hegde SK, Ditunno JF Jr: Age effect on prognosis for functional recovery in acute, traumatic central cord syndrome.  Arch Phys Med Rehab 1990;71:963-968.Northrup BE: Acute injuries to the spine and spinal cord: Evaluation and early treatment, in Clark CR (ed): The Cervical Spine, ed 4.  Philadelphia, PA, Lippincott Williams & Wilkins, 2005, p 735.

Question 2149

Topic: 6. Spine

What type of injury is considered the major mechanism of cervical fracture, dislocation, and quadriplegia in contact sports and diving?

. Flexion
. Extension
. Flexion-compression
. Flexion-distraction
. Flexion-rotation

Correct Answer & Explanation

. Flexion

Explanation

DISCUSSION: A compression or burst injury occurs with vertical loading of the spine, such as from a blow to the vertex with the neck flexed (eg, spear tackling in football).  This leads to vertebral end plate fractures before disk injury.  At higher forces, the entire vertebra and disk may explode into the spinal canal.  Analysis has shown this to be the major mechanism of cervical fracture, dislocation, and quadriplegia.  With the normal head-up posture, the cervical spine has a gentle lordotic curve, and forces transmitted to the head are largely dissipated in the cervical muscles.  When the neck is flexed, the cervical spine becomes straight, with the vertebral bodies lined up under one another.  This allows for minimal dissipation of the impact forces to be absorbed by the neck muscles.REFERENCES: Cantu RC: Head and spine injuries in youth sports.  Clin Sports Med 1995;14:517-532.Proctor MR, Cantu RC: Head and neck injuries in young athletes.  Clin Sports Med 2000;19:693-715.Torg JS: Epidemiology, pathomechanics, and prevention of athletic injuries to the cervical spine.  Med Sci Sports Exerc 1985;17:295-303.

Question 2150

Topic: 6. Spine

A 21-year-old woman with Marfan syndrome is seeking evaluation of her scoliosis. She reports no back or leg pain, and the neurologic examination is normal. Lateral and bending radiographs are shown in Figures 7a through 7e. Management should consist of

. observation and regular follow-up.
. a custom-molded thoracolumbar orthosis.
. anterior spinal fusion from T10 to L4.
. anterior and posterior spinal fusion from T10 to L4.
. posterior spinal fusion from T4 to L4.

Correct Answer & Explanation

. observation and regular follow-up.

Explanation

DISCUSSION: Because the patient’s thoracolumbar scoliosis is of a large enough magnitude, observation or bracing is not recommended.  The thoracolumbar curve is flexible enough and L4 corrects well enough to the pelvis to consider anterior spinal fusion from T10 to L4.REFERENCES: Garfin SR, Vaccaro AR (eds): Orthopaedic Knowledge Update: Spine.  Rosemont, IL, American Academy of Orthopaedic Surgeons, 1997, pp 161-171.Turi M, Johnston CE II, Richards BS: Anterior correction of idiopathic scoliosis using TSRH instrumentation.  Spine 1993;18:417-422.Moskowitz A, Trommanhauser S: Surgical and clinical results of scoliosis surgery using Zielke instrumentation.  Spine 1993;18:2444-2451.

Question 2151

Topic: 6. Spine

A 55-year-old woman with a history of untreated idiopathic scoliosis has had neurogenic claudication for the past several months. MRI reveals spinal stenosis at L2-L3, L3-L4, and L4-L5. Radiographs show a 45° lumbar curve from T10 to L4, with a degenerative spondylolisthesis at L4-L5. Laminectomy at the stenotic levels and stabilization of the deformity are planned. Which of the following is NOT considered an absolute indication for extending the fusion to the sacrum, rather than stopping at L5?

. Advanced degenerative disk disease with facet arthrosis at L5-S1
. Decreased T2 signal in the L5-S1 disk with normal facet joints
. Previous laminectomy at L5-S1
. Fixed tilt of L5 with severe unilateral facet arthrosis
. Spondylolysis bilaterally at L5

Correct Answer & Explanation

. Advanced degenerative disk disease with facet arthrosis at L5-S1

Explanation

DISCUSSION: There are several indications for extending adult scoliosis fusions to the sacrum, rather than stopping in the lower lumbar spine.  These indications include posterior column deficiencies at L5-S1, such as spondylolysis and laminectomy, and deformities extending to the sacrum, such as fixed tilt of L5-S1 or sagittal imbalance.  MRI signal changes in the L5-S1 disk do not preclude stopping the fusion at L5.  Some surgeons use diskography or diagnostic facet blocks to evaluate the integrity of the L5-S1 level prior to stopping the fusion at L5.  Long scoliosis fusions stopping at L5 have a significant risk of failure, highlighting the importance of careful selection of fusion levels.REFERENCES: Bradford DS, Tay BK, Hu SS: Adult scoliosis: Surgical indications, operative management, complications, and outcomes.  Spine 1999;24:2617-2629.Bridwell KH: Where to stop the fusion distally in adult scoliosis: L4, L5, or the sacrum?  Instr Course Lect 1996;45:101-107.Edwards CC II, Bridwell KH, Patel A, et al: Long adult deformity fusions to L5 and the sacrum: A matched cohort analysis.  Spine 2004;29:1996-2005.

Question 2152

Topic: 6. Spine

Figures 33a and 33b show the standing posteroanterior and lateral radiographs of a 59-year-old woman with adult idiopathic scoliosis. She underwent a prior decompressive laminectomy and fusion at L4-S1 to address lumbar stenosis. She now reports progressive lower back pain and a feeling of being shifted to the right. If surgical intervention is considered, what is the most important goal in improving her health-related quality of life (HRQL) outcomes? Review Topic

. Correction of the thoracolumbar curve
. Sagittal balance
. Coronal balance
. Correction of the thoracic curve
. Shoulder balance

Correct Answer & Explanation

. Correction of the thoracolumbar curve

Explanation

Sagittal balance is the most reliable predictor of clinical symptoms and HRQL outcomes on the SRS 29, SF-12, and Oswestry Disability Index. Coronal balance, shoulder balance, curve magnitude, and degree of curve correction are less critical in determining clinical symptoms and outcomes.(SBQ12SP.24) A 39-year-old man presents to clinic with a 3-week history of low back pain that radiates to the right lower extremity. On examination, he has mildly decreased sensation over the dorsum of the foot and positive straight leg raise on the right side. MRI images are shown in Figure A and B. Which of the following is true regarding this patient's condition?Review TopicNonoperative management with NSAIDS and physical therapy is effective for 50% of patientsSurgical treatment is indicated in patients with diminished sensationSurgical treatment is equivalent to nonoperative management in terms of pain and functionGood surgical outcome is associated with mainly back complaintsSize of disc herniations typically decrease over time without surgical interventionThe patient is presenting with a lumbar disc herniation at the L4-L5 level. The size of disc herniations decrease in most patients over time without surgical intervention.Lumbar disc herniations are the result of recurrent torsional strain, which leads to small tears of the annulus fibrosus, ultimately allowing herniation of the nucleus pulposis. First line treatment consists of NSAIDS, muscle relaxants and physical therapy and is effective in 90% of patients. Second line treatment typically involves epidural and selective nerve root corticosteroid injections. Microdiscectomy is reserved for patients with more than 6 weeks of disabling pain that has failed nonoperative management, progressive weakness, or cauda equina syndrome.In the Spine Patient Outcomes Research Trial (SPORT), Weinstein et al. investigated patient outcomes and satisfaction after operative and nonoperative management of lumbar disc herniations. While the randomized arm of the study did show statistically significant differences in the intent-to-treat analysis due to significant crossover of patients, the observational cohort revealed a significant improvement in pain, function, and disability for patients treated with surgery versus nonoperative measures.Benson et al. looked at the natural history of massive herniated discs in 37 patients with 7-year follow up. They found a more than 60% reduction in disc size over this time period. Reduction in disc size did not correlate with clinical improvement.Figure A and B are sagittal and axial T2 MRI images, respectively, showing a right sided lumbar disc herniation at the L4-L5 level.Incorrect Answers:

Question 2153

Topic: 6. Spine

A patient who has had neck pain radiating down the arm for the past 4 weeks reports that the pain was excruciating during the first week. Management consisting of anti-inflammatory drugs and physical therapy has decreased the neck and arm symptoms from 10/10 to 3/10. He remains neurologically intact. MRI and CT scans are shown in Figures 5a and 5b. The best course of action should be

. immediate hospital admission and surgery because of the risk of paralysis.
. surgery within 24 hours.
. surgery within the next several days.
. elective surgery at the next available surgical date.
. additional nonsurgical management.

Correct Answer & Explanation

. immediate hospital admission and surgery because of the risk of paralysis.

Explanation

DISCUSSION: Although the patient has a large herniated nucleus pulposus, the pain has decreased from 10/10 to 3/10 over a 4-week period and the patient is now free of any neurologic symptoms.  It is quite likely that further nonsurgical management will continue to resolve his symptoms.  In the absence of any neurologic deficits, there is no evidence that the patient is at significant risk for paralysis.REFERENCES: Saal JS, Saal JA, Yurth EF: Nonoperative management of herniated cervical intervertebral disc with radiculopathy.  Spine 1996;21:1877-1883.Komori H, Shinomiya K, Nakai O, Yamaura I, Takeda S, Furuya K: The natural history of herniated nucleus pulposus with radiculopathy.  Spine 1996;21:225-229.

Question 2154

Topic: 6. Spine

A full-term newborn has webbing at the knees, rigid clubfeet, a Buddha-like posture of the lower extremities, and no voluntary or involuntary muscle action at and below the knees. Radiographs of the spine and pelvis reveal an absence of the lumbar spine and sacrum. What maternal condition is associated with this diagnosis?

. Alcoholism
. Drug abuse
. Down syndrome
. Diabetes mellitus
. Idiopathic scoliosis

Correct Answer & Explanation

. Alcoholism

Explanation

DISCUSSION: The history, physical examination, and radiographic findings are consistent with type IV sacral agenesis or caudal regression syndrome.  These children are born with no lumbar spine or sacrum.  The T12 vertebra is often prominent posteriorly.  Popliteal webbing and knee flexion contractures are common with this diagnosis.  There is a higher incidence of this diagnosis when the mother has diabetes mellitus.  Maternal drug abuse and alcoholism can produce phenotypically unique children but without the findings described here.  Maternal idiopathic scoliosis is not associated with caudal regression syndrome.REFERENCES: Chan BW, Chan KS, Koide T, et al: Maternal diabetes increases the risk of caudal regression caused by retinoic acid.  Diabetes 2002;51:2811-2816.Zaw W, Stone DG: Caudal regression syndrome in twin pregnancy with type II diabetes.J Perinatol 2002;22:171-174.

Question 2155

Topic: 6. Spine

Central cord syndrome would most likely be seen in which of the following patients? Review Topic

. year-old male following hyperextension cervical injury
. year-old male following penetrating trauma to the neck
. year-old male following hyperflexion cervical injury
. year-old male following surgical aortic aneurysm repair
. year-old male without a traumatic mechanism

Correct Answer & Explanation

. year-old male following hyperextension cervical injury

Explanation

Central cord syndrome is an incomplete spinal cord injury most commonly seen in older patients following hyperextension cervical injury.Central cord syndrome is most commonly caused by cervical hyperextension in older patients with underlying cervical spondylosis. It is thought to be due to compression between anterior osteophytes and posterior infolded ligamentum flavum during hyperextension. This preferentially affects the motor tracks closest to midline, and thus motor function is impaired greater than sensation, and upper extremities more affected than lower extremities (remember upper motor tracks are more central in the lateral corticospinal tract)Nowak et al. present a review article on central cord syndrome. They cite the most common cause of central cord syndrome as a hyperextension mechanism in an elderly patient with preexisting spondylosis.Gupta et al. present a review article on the management of spinal cord injuries. They discuss advances and ongoing study in acute management, surgical techniques, pharmacoptherapies, and cellular transplantation. They recommend a multidisciplinary approach to treating spinal cord injuries.Dvorak et al. present results of long term follow-up after traumatic central cord syndrome. They found average improvement of ASIA motor scores (AMS) from 58.7 to 92.3. Bowel and bladder control returned in 81% and independent ambulation returned in 86%. Variables correlated with final AMS were AMS at injury, formal education, and presence of spasticity during follow-up.Illustration A shows the blood supply to the spinal cord. Illustration B shows the area affected by central cord syndrome to help explain why it produces the described deficits.Incorrect answers:may be seen in the presence of congenital cervical stenosis. However, this is not the most common cause. Answer 4: Aortic aneurysm repair would more commonly lead to anterior cord syndrome.

Question 2156

Topic: 6. Spine

A 35-year-old man with a history of spine surgery 5 years ago reports the recent development of frequent low back pain radiating to the legs. The patient blames a low-energy fall that occurred 9 months ago for the recent symptoms. Radiographs reveal previous interbody fusions of L4-L5 and L5-S1, with hardware present. The vertebrae appear well-fused and stable. What is the most likely cause of the low back pain? Review Topic

. Increased range of motion and strains at L3-L4
. A herniated disk due to the fall
. A compression fracture
. Development of pseudarthrosis due to failure of the previous fusions
. Loosening of the hardware that was used for the previous fusions

Correct Answer & Explanation

. Increased range of motion and strains at L3-L4

Explanation

It is increasingly recognized in the spine literature that fusion of two or more vertebrae produces increased range of motion in adjacent motion segments, resulting in increased stresses and, with time, degeneration of the adjacent disks. Loss of disk height would be an initial indication of disk degeneration. If the patient's fall had caused a fracture, the symptoms would have been immediate.

Question 2157

Topic: 6. Spine

What is the most appropriate treatment at this time?

. IV steroids and antibiotics
. IV antibiotics
. Anterior decompression and fusion
. Posterior laminectomy and instrumented fusion

Correct Answer & Explanation

. IV steroids and antibiotics

Explanation

DISCUSSIONPrompt diagnosis and treatment of patients with spinal epidural abscess is crucial to maintain and/or improve neurologic function. This clinical scenario stresses the importance of advanced imaging studies. It is also important to recognize the imaging features of spinal epidural abscess. T1-weighted gadolinium-enhanced images show ring enhancement with a central nonenhancing, low-signal area. In such a case, urgent decompression is indicated. Because of the location of the abscess, which is anterior to the spinal cord, an anterior decompression and reconstruction (ie, fusion) is probably the best treatment plan. Steroids are contraindicated in the presence of an epidural abscess. IV antibiotics alone will not adequately treat a patient with a neurological deficit. A posterior laminectomy and fusion will not safely allow access to the abscess.RECOMMENDED READINGSBluman EM, Palumbo MA, Lucas PR. Spinal epidural abscess in adults. J Am Acad Orthop Surg. 2004 May-Jun;12(3):155-63. Review. PubMed PMID: 15161168.View Abstract at PubMedGhobrial GM, Beygi S, Viereck MJ, Maulucci CM, Sharan A, Heller J, Jallo J, Prasad S, Harrop JS. Timing in the surgical evacuation of spinal epidural abscesses. Neurosurg Focus. 2014 Aug;37(2):E1. doi: 10.3171/2014.6.FOCUS14120. PubMed PMID: 25081958.ViewAbstractat PubMedThis is the last question of the exam.

Question 2158

Topic: 6. Spine

A 55-year-old man reports increasing weakness in his arms that has progressed to his lower limbs, resulting in frequent tripping and falling. Examination reveals weakness in shoulder abduction and external and internal rotation bilaterally. Fasciculation is noted. He also has weakness in elbow flexion and extension bilaterally, and his grip strength is diminished. An electromyogram and nerve conduction velocity studies show decreased amplitude of compound motor action potential, slightly slowed motor conduction velocity, and denervation signs with decreased recruitment in all extremities. The sensory study is normal. Based on these findings, what is the most likely diagnosis?

. Syrinx of the cervical spine
. Intracranial mass
. Myasthenia gravis
. Amyotrophic lateral sclerosis (ALS)
. Fascioscapulohumeral dystrophy

Correct Answer & Explanation

. Syrinx of the cervical spine

Explanation

DISCUSSION: The major determinant of ALS (Lou Gehrig disease) is progressive loss of motor neurons.  The loss usually begins in one area, is asymmetrical, and later becomes evident in other areas.  The first signs of ALS may include either upper or lower motor neuron loss.  Recognition of upper motor neuron involvement depends on clinical signs, but electromyography and nerve conduction velocity studies can help identify lower motor neuron involvement.  Electrodiagnostic abnormalities in three or more areas are required to make a definitive diagnosis.  The motor unit potentials (MUPs) changes in ALS include impaired MUPs recruitment, unstable MUPs, and abnormal MUPs size and configuration.  A number of abnormal spontaneous discharges can occur with ALS, especially fibrillation potentials and fasciculation potentials.  In ALS, the motor nerve conduction study will be abnormal, but a co-existing normal sensory study is definitive for this disease.REFERENCES: de Carvalho M, Johnsen B, Fuglsang-Frederiksen A: Medical technology assessment: Electrodiagnosis in motor neuron diseases and amyotrophic lateral sclerosis.  Neurophysiol Clin 2001;31:341-348.Daube JR: Electrodiagnostic studies in amyotrophic lateral sclerosis and other motor neuron disorders.  Muscle Nerve 2000;23:1488-1502.Troger M, Dengler R: The role of electromyography (EMG) in the diagnosis of ALS.  Amyotroph Lateral Scler Other Motor Neuron Disord 2000;1:S33-S40.

Question 2159

Topic: 6. Spine

In the evaluation of somatosensory-evoked potential waveforms for intraoperative neuromonitoring for spinal surgery, the minimum criteria for determining potentially significant changes include Review Topic

. 10% decrease in amplitude, 50% decrease in latency.
. 10% decrease in amplitude, 50% increase in latency.
. 0% loss of amplitude, transient increase in latency.
. 50% decrease in amplitude, 10% increase in latency.
. 50% decrease in amplitude, 10% decrease in latency.

Correct Answer & Explanation

. 10% decrease in amplitude, 50% decrease in latency.

Explanation

The established criteria for interpreting a significant change are 50% decrease in signal amplitude, 10% latency increase, and/or a complete loss of potential. Intraoperative spinal cord monitoring during spinal surgery generally consists of a combination of monitoring modalities. Somatosensory-evoked potentials in combination with intraoperative electromyography can provide adequate coverage of sensory and motor components of spinal cord and nerve root function. Significant changes in evoked potential waveform characteristics can reflect dysfunction of the ascending somatosensory system.

Question 2160

Topic: 6. Spine

Which of the following complications is uniquely associated with an anterior approach to the lumbosacral junction?

. Nerve root injury
. Erectile dysfunction
. Dural tear
. Pulmonary embolism
. Retrograde ejaculation

Correct Answer & Explanation

. Nerve root injury

Explanation

DISCUSSION: Retrograde ejaculation is a sequela of injury to the superior hypogastric plexus.  The structure needs protection, especially during anterior exposure of the lumbosacral junction.  The use of monopolar electrocautery should be avoided in this region.  The ideal exposure starts with blunt dissection just to the medial aspect of the left common iliac vein, sweeping the prevertebral tissues toward the patient’s right side.  Although erectile dysfunction can be seen after spinal surgery, it is not typically related to the surgical exposure because erectile function is regulated by parasympathetic fibers derived from the second, third, and fourth sacral segments that are deep in the pelvis and are not at risk with the anterior approach.  The other choices are complications of spinal surgery but are not uniquely associated with an anterior L5-S1 exposure.REFERENCES: Flynn JC, Price CT: Sexual complications of anterior fusion of the lumbar spine.  Spine 1984;9:489-492.Watkins RG (ed): Surgical Approaches to the Spine, ed 1.  New York, NY, Springer-Verlag, 1983, p 107.An HS, Riley LH III: An Atlas of Surgery of the Spine.  New York, NY, Lippincott Raven, 1998, p 263.

Test Yourself

Switch to an interactive, timed exam simulation to truly master this topic.

On this Page